Snowmobile suspension system

ABSTRACT

To enable a rider to control in real time the type of ride he desires, a snowmobile is equipped with a suspension system that includes at least one fluid actuated device which can be adjusted in real time to control the relative distance between the body of the snowmobile onto which the rider sits and the frame, or the slide tracks about which the drive belt is mounted. By setting a constant predetermined desirable distance between the body and the slide tracks, or the frame, of the snowmobile, an optimal cushioned ride for the rider is obtained. The control of the fluid actuated device(s) may be effected at any time manually by the rider, or be effected by a feedback system. The snowmobile is also equipped with an ABS system for enhancing the traction of the drive belt on snow and therefore the control of the snowmobile by the rider.

FIELD OF THE INVENTION

The present invention relates generally to snowmobiles and moreparticularly to a suspension system that provides a controlled cushionedride for riders of the snowmobile.

BACKGROUND OF THE INVENTION

To compensate for the ruggedness of the terrain, a conventionalsuspension system for a snowmobile includes a pair of shock absorbers,and associated springs, for supporting the frame of the snowmobile. Suchsuspension system is usually not adjustable. Thus, if persons ofdifferent weights, or for that matter if more than one person, were toride on the same snowmobile, the ride would become choppy and thesteering of the snowmobile becomes less responsive. Suchunresponsiveness in the steering and choppiness in the ride detract fromthe rider the pleasure of driving or riding a snowmobile.

The fact that the conventional suspension system of snowmobiles isunable to adjust on a real time basis means that a rider has to stop thesnowmobile, turn off the engine for safety sake and manually adjust thestiffness or tension provided by the shock absorbers of the snowmobile,if indeed such shock absorbers were adjustable. But adjusting theconventional suspension system for one environment means that the riderhas to readjust the suspension system when the snowmobile is ridden in adifferent environment, as the suspension system, once set, remains setat that tension or stiffness, until readjustment.

SUMMARY OF THE INVENTION

To provide a smooth or cushioned ride for a rider of the snowmobile andalso the ability of the rider to adjust at any time the stiffness of theride, at least one but most likely a plurality of fluid actuated devicesare interposed between the body and the frame of the snowmobile. Thesefluid actuated devices could be hydraulic or gas driven cylinderscontrolled either manually by the rider or automatically by a feedbackcircuit.

For supplying fluid—which per the instant invention encompasses air,gas, hydraulic oil and other incompressible fluids—to the fluid actuatordevices, valve mechanisms which may include throttle valves and pressureregulators are used. To provide the necessary pressure, a compressor isused. The fluid is stored in one or more fluid containers or reservoirs,which are communicatively connected to the fluid actuator devices byfluid conduits. The throttle valves and pressure regulators provide thenecessary regulation of the amount of fluid supplied to the fluidactuated devices. And depending on the kind of stiffness the riderdesires, different amounts of fluid may be provided independently toeach of the plurality of fluid actuated devices. The amount of fluidsupplied to each of the fluid actuated cylinders can vary, as fluidcompensation may vary for each of the cylinders.

The fact that the stiffness of each of the fluid actuated cylinders canbe adjusted means that riders of different weights may each comfortablyride on the same snowmobile. And for those instances where there aremore than one rider, the riding comfort of the snowmobile is notdecreased insofar as the cushioning ability of the fluid actuatedcylinders can be adjusted for the increased weight.

To free the rider the need to manually adjust the fluid actuateddevices, a feedback circuit including a sensor and a processor may beused for obtaining the optimal cushioned ride for the rider. One way inwhich the optimal cushioned ride may be obtained is by the sensormonitoring the distance separating the slide tracks of the snowmobilewhich come into contact with the terrain and the body of the snowmobilewhich is mounted to a frame to which the slide tracks are coupled. Bymaintaining a given distance which could be ascertained empirically, andcontrolling the fluid actuated cylinders to raise or lower the body ofthe snowmobile relative to its frame or slide tracks, the optimalcushioned ride can be maintained.

The same type of fluid actuated cylinder could be used to connect theskis to the body of the snowmobile so that better controlled and morestabilized steering is achieved.

To provide yet better handling and control, the snowmobile of theinstant invention is equipped with an anti-lock braking system (ABS).

It is therefore an objective of the present invention to provide a newand improved suspension system that gives a rider of a snowmobile anoptimal cushioned ride.

It is yet another objective of the present invention to provide eachrider of the instant invention snowmobile the ability to control thetype of ride he desires, either manually or automatically.

It is yet another objective of the present invention to provide eachrider of the instant invention snowmobile the ability to control thetype of ride he desires, either manually or automatically.

It is moreover another objective of the present invention to provide asnowmobile with a controlled and stabilized steering system.

It is still another objective of the present invention to provide asnowmobile with improved handling abilities by equipping the same withan ABS brake system.

BRIEF DESCRIPTION OF THE FIGURES

The above-mentioned objects and advantages of the present invention willbecome apparent and the invention itself will be best understood byreference to the following description of the present invention taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the basic body and frame of aconventional snowmobile being used for illustrating the instantinvention;

FIG. 2 is a simplified illustration of the instant invention;

FIG. 3 is a perspective view of the frame and slide tracks illustratingan embodiment of the instant invention;

FIG. 4a is a cross-sectional cut-away view of an exemplar fluid actuateddevice of the instant invention;

FIG. 4b is a side view of the exemplar fluid actuated device of theinstant invention sans the rubber isolator; and

FIG. 5 is a simplified schematic illustrating the addition of an ABSbraking system to the instant invention vehicle.

DETAILED DESCRIPTION OF THE INVENTION

Stripped of all components not required for the understanding of theinstant invention, an exemplar snowmobile showing only the body and theframe attached thereto is shown in FIG. 1. As illustrated, snowmobile orvehicle 2 has a body 4 mounted to a frame 6 by way of a number ofconnecting links and struts. Fixedly coupled to frame 6 are two slidetracks 8 a and 8 b about which a belt, not shown, is mounted. As is wellknown, the belt is driven by at least one wheel, which in turn is drivenby a belt or gears from a transmission, shown in FIG. 5, which movementis driven by an engine, not shown for the sake of simplicity inillustration. Thus, when driven, the belt is guided by slide tracks 8 aand 8 b, as well as guide wheels, and rotates about the frame ofsnowmobile 2 such as for example shown by the dotted line 30 in FIG. 3.

Also shown in FIG. 1 are a number of shock absorbers 10 and 12interposed between body 4 and frame 6 for providing a smoother ride fora rider of the snowmobile. The problem with such conventional supportprovided by shock absorbers 10 and 12 is that those shock absorbers arenot adjustable and thus if the weight of the rider, or riders, exceeds acertain predetermined weight, body 4 of the snowmobile tends to sag ontoframe 6, and any irregularity on the path would cause body 4 to bumpagainst frame 6, thereby providing a not so comfortable ride for therider. Further, given the one for all mentality of the prior artsuspension system for snowmobiles, different riders of the samesnowmobile may feel differently when the snowmobile is in movement, andthereby possibly causing uneven handling of the snowmobile which maylead to potential accidents.

The shock absorbers of some snowmobiles do allow for adjustment.However, in order to adjust those shock absorbers, the rider has to inall likelihood turn the snowmobile over and manually rotate the shockabsorber to a given height. And if after adjustment, the rider stillfeels he is not getting an optimal cushioned ride, he has to yet againstop the snowmobile, turn it over, and readjust the shock absorbers.Needless to say, such stop and go, not to mention adjustment of theshock absorbers by trial and error, is both time consuming andfrustrating for the rider.

With reference to FIG. 2, the suspension system of the present inventionsnowmobile is shown. As illustrated, body 4 of the vehicle, shown by thedotted line 4 b,is positioned relative to frame 6 of the vehicle. Takingaway all of the linkages and connecting members that are not necessaryfor the understanding of this invention, FIG. 2 shows body 4 to beconnected to frame 6 by means of two fluid actuated devices 14 and 16,otherwise also referred to as fluid driven cylinders. As shown, each ofcylinders 14 and 16 has a first end 14 a and 16 a, respectively,connected to body 4. The respective connection points to the body of thesnowmobile by the corresponding fluid actuated cylinders, for theexemplar embodiment shown in FIG. 2, are coincident with guiding wheels18 and 20. At least one other guiding wheel, namely 22, is shown in theexemplar embodiment of the snowmobile of FIG. 2. To effect movement ofbelt 30, a drive wheel 24 driven by either a drive belt or gear isshown.

As illustrated, belt 30 is mounted about slide tracks 8 and is guided bythe various guide wheels and driven by drive wheel 24 to effect movementof the snowmobile. Further with respect to fluid actuated cylinders 14and 16, note that each of those devices has a second respective end 14 band 16 b moveably coupled to frame 6, and therefore slide tracks 8. Forthe embodiment illustration of FIG. 2, assume that slide tracks 8 arepart of frame 6. Further note that although fluid driven cylinders 14and 16 are shown to be positioned in an offset position, the way inwhich those cylinders are positioned relatively to body 4 and frame 6 isnot of import to this invention, insofar as those cylinders can bepositioned in numerous ways, for different embodiments. Furthermore,note that although two fluid driven cylinders are shown, in actualityonly one or additional similar cylinders may also be used.

Further with respect to FIG. 2, note that each of cylinders 14 and 16 isprovided with at least one inlet/outlet port 14 c and 16 c,respectively, to which corresponding fluid conduits 26 and 28 arecommunicatively connected. As shown, conduits 26 and 28 are alsocommunicatively connected to fluid stores 30 and 32, respectively. Fluidstores 30 and 32 each act as a reservoir of a fluid. For this invention,fluid is defined to encompass at least air, different gases, hydraulicoil and/or other incompressible liquids.

For the exemplar vehicle of FIG. 2, spliced to fluid conduits 26 and 28are respective throttle valves 34 and 36. These valves, as is wellknown, control the amount of fluid provided to respective fluidcylinders 14 and 16. The operation of throttle valves 34 and 36 may becontrolled by a processor 38. A more detailed discussion of theoperation of throttle valves 34 and 36, as well as the overall operationof the system, is given infra.

To provide the requisite pressure to fluid stores 30 and 32, acompressor 40, by way of a conduit 42, outputs pressurized fluid tofluid stores 30 and 32. For the exemplar embodiment shown in FIG. 2, toregulate the amount of pressure in fluid stores 30 and 32, respectivepressure regulators 44 and 46 are interposed between conduit 42 and therespective input port of the fluid stores. Thus, in the case of airbeing the fluid of choice, pressurized air could be pumped fromcompressor 40 into fluid stores 30 and 32, which in this instance act asair tanks. The pressurized air is then provided, and controlled bythrottle valves 34 and 36, to fluid cylinders 14 and 16, which in thisinstance are air driven cylinders, to control the distance separatingbody 4 and frame 6, i.e., slide tracks 8.

In other words, the distance separating body 4, as for example from theline designated 4 b thereof, to slide tracks 8 which via belt 30 is incontact with the ground, can be varied by adjusting the amount of fluidprovided to fluid cylinders 14 and 16, either independently or incombination. Thus, body 4 and frame 6, or slide track 8, are movablerelative to each other by the amount of fluid provided to fluidcylinders 14 and 16. Putting it differently, the stiffness of fluidcylinders 14 and 16 can be varied to compensate for different weightsbeing placed on body 4, with respect to the relationship between body 4and frame 6. Thus, irrespective of the weight of the rider, or riders,placed onto body 4, the suspension of the instant invention is able tocompensate for such variants in weight by simply adjusting the amount offluid, pressurized or otherwise, in fluid cylinders 14 and 16. And thisadjustment can be effected in a real time basis, by the rider, eitherwhen he first sits on the snowmobile or when the vehicle is in movement.

To elaborate, further reference FIG. 2. There, a sensor 48 provided insnowmobile 2 is shown to be positioned relative to body 4 and frame 6,so as to be able to monitor the relative position of body 4, at leastwith respect to its base line 4 b, to frame 6, or slide tracks 8. Suchmonitored signal is provided to processor 38 which can output thereceived signal to a gauge or readout 50 for the rider. The rider inturn has the option of manually actuating either compressor 40 orregulator valves 44 and 46 (and possibly throttle valves 34 and 36) toadjust the amount of fluid supplied to fluid cylinders 14 and 16.

Alternatively, the rider has the option of letting processor 38automatically adjust the a mount of clearance body 4 has with respect toframe 6 by allowing processor 38 to regulate the different operations ofcompressor 40, regulator valves 44 and 46, as well as throttle valves 34and 36. Processor 38 does this in receipt of the output signal fromsensor 48, a nd in fact can continuously adjust the amount of fluidprovided to fluid cylinder s 14 and 16 in response to the output signalfrom sensor 48 which continuously varies if the snowmobile is inmovement. By thus continuously varying the amount of fluid provided tofluid cylinders 14 and 16, provided that a presumed optimal cushionedride or threshold has been preset by the rider, an optimal cushionedride is maintained, irrespective of the type of movement of vehicle 2.The rider can override the feedback operation of processor 38 bymanually adjusting, at any time, the stiffness of his ride by adjustingthe amount of fluid being provided to fluid cylinders 14 and 16, eitherempherically or by viewing the readout from gauge 50.

In addition to sensing the relative movement between body 4 and slidetracks 8, the present invention suspension system can optionally mountanother sensor 52 to vehicle 2 for measuring the weight placed on body4, such as for example by the rider or riders. Upon sensing this weight,sensor 52 provides an output signal to processor 38, which thenautomatically adjusts the relative distance separating body 4 and frame6 by regulating the amount of fluid provided to fluid cylinders 14 and16, thereby effecting the optimum ride for the given weight sensed. Thepresumed optimal cushioned ride for a given weight of course can bepreset or predetermined.

As is well known, snowmobiles have skis for steering. One such ski isshown in FIG. 2 as 52. To have stabilized steering, the exemplarsnowmobile of FIG. 2 has movably coupled to ski 52 a fluid actuateddevice 54 similar to the fluid actuated cylinders discussed above. Tocontrol the operation of fluid actuated cylinder 54, fluid is providedthereto per its inlet/outlet port 54 c by way of a fluid conduit 56,which has attached thereto a throttle valve 58. Fluid conduit 56,similar to the earlier fluid conduits, is connected to a fluid store 60.The amount of pressure or fluid provided to fluid store 60 is likewiseprovided thereto by compressor 40 via conduit 42. A regulator valve 62is interposed between conduit 42 and fluid store 60 for regulating thepressure of the fluid input thereto. By thus provisioning the steeringmechanism of snowmobile 2 with an adjustable fluid actuator, thesteering is controlled and stabilized. As before, the amount of fluid,and/or the pressure provided to fluid cylinder 54, can be adjusted byprocessor 38 on a real time basis, by means of a feedback circuit thatsenses the pressure ski 52 is subjected to, as well as the types ofmovement such as sharp cornering, being effected on the steeringmechanism. As before, the amount of fluid provided to fluid cylinder 54can be manually regulated by the rider.

One further point with respect to the FIG. 2 embodiment. Note that eventhough a compressor, and various valves, are illustrated to be used inthe suspension system thereof, it should be appreciated that, in certaincircumstances, no such valves or compressor are necessary, as a fluidstore that is under a predetermined amount of pressure can be used. Inthose instances, throttle valves may be provided to allow fluid totraverse between an air cylinder and a fluid store in a regulatedmanner, so that as more pressure is being applied to the air cylinder(which may be due to forces acting on the slide tracks resulting fromthe weight of body 4 and any rider thereon as well as the movement ofthe vehicle), more fluid is supplied to the air cylinder to compensatefor the reactive forces to thereby maintain the desired stiffness andthe desired ride. The same is true with respect to the earlierdiscussion of the operation of the FIG. 2 suspension system in that theweight of the rider or riders on body 4 causes a counter reaction by theair cylinders to thereby provide an optimal cushioned ride for therider.

FIG. 3 is perspective view of an exemplar frame 6 of the instantinvention snowmobile illustrating in particular the suspension systemthereof. As shown, slide tracks 8 a and 8 b are coupled to frame 6 byconventional means such as links, rods, nuts and bolts. Frame 6 in turnis comprised of support bars 56 a and 56 b that support a spindle aboutwhich guide wheels 20 a and 20 b are mounted. For the exemplarembodiment frame of FIG. 3, two torsion springs 58 a and 58 b aremounted about the spindle of guiding wheels 20 a and 20 b. Also mountedto this spindle is one end of fluid actuated cylinder 16, which otherend is mounted to the base of frame 6. In place of torsion springs 58 aand 58 b, it should be appreciated that rigid rods that couple thespindle to the lower portion of frame 6 may also be used. Such rigidrods would in essence be positioned relatively in parallel to supportbars 56 a and 56 b.

Further shown in the exemplar frame 6 of FIG. 3 are additional supportbars 60 a and 60 b that, along with a frontal support rod 62, providerigidity to frame 6. As shown, mounted to frontal support rod 62 is thefirst end of fluid actuated cylinder 14, whose other end is connected toa lower support bar of frame 6. Thus positioned, fluid actuatedcylinders 14 and 16 provide support to the body of the snowmobile whichis positioned thereover. Note that for the sake of simplicity ofillustration, the inlet/outlet ports of fluid actuated cylinders 14 and16 are not shown in the FIG. 3 embodiment.

The construction of an exemplar fluid actuated cylinder of the instantinvention is shown in greater detail in FIGS. 4a and 4 b. For thisdiscussion, assume that the fluid actuator cylinder of FIGS. 4a and 4 brepresents fluid actuator cylinder 14 shown in FIG. 2 so that the samecomponents are designated with the same numbers. As shown, fluidactuated cylinder has a first end 14 a and a second end 14 b. Furthershown is the inlet port 14 c through which fluid is provided to andtaken out of fluid cylinder 14. As best shown in FIG. 4b, a portion ofthe fluid actuated cylinder comprises a shock isolator 62 havingportions 62 a and 62 b that interact with each other on the load. Asbest shown in FIG. 4a, a rubber isolator such as that made by theFirestone company under part No. 7010 is integrated about the upperportion of portion 62 a. This rubber isolator, designated 54 in FIG. 4a,is attached to portion 62 b by means of a threaded portion 66. The upperend of isolator 64 in turn is coupled to a collar 68 of portion 62 a.Needless to say, isolator 64 is secured to body 62 in a gas-tightfashion so that any fluid provided therein remains in the interior ofisolator 64. Moreover, it should be noted that isolator 64 is made of arubber that has a sufficiently strong characteristic so that ifsufficient fluid, pressurized or otherwise, is provided therein, end 14a and end 14 b are movable relative to each other by the expansion ofisolator 64. The amount of isolation, or stiffness, provided isdependent on the amount of fluid input to the chamber 70 of isolatorrubber 64. Thus, when filled with fluid, piston 72 of absorber 62 ismoved relative to end 14 b, thereby effecting an extension of fluidactuated cylinder 14. For the embodiment shown in FIG. 4a, the fluidused could be either air or gas. Of course, properly reconfigured,instead of a gas or air actuated device, fluid actuator cylinder 14could be driven by hydraulic oil and/or other incompressible fluids.

FIG. 5 illustrates another aspect of the instant invention snowmobile.In particular, FIG. 5 illustrates the equipping of the snowmobile of theinstant invention with an anti-lock braking system (ABS). As shown,drive wheel 24 is driven by a drive belt 74 which is in turn driven by awheel, not shown, coupled to a disc plate 76. Plate 76 is connected tothe driving gears of a transmission 78 of the vehicle that translatesthe movement of an engine, not shown. To effect the ABS system, a brakemechanism 80 is mounted relatively to transmission 78 to be in brakingrelationship with disc plate 76. The fluid provided to operate brake pad80 is input from a fluid conduit 82, which is connected to a solenoidvalve unit 84. Valve unit 84 in turn is connected to a master cylinder,not shown, and operatively connected to an actuator 86, which may bemounted to the handle of the snowmobile. For feedback, a processorcontroller 88, which may actually be incorporated as part of mainprocessor 38, is used.

The reason that ABS braking is advantageous for the instant inventionsnowmobile is that drive belt 38 which makes actual contact with thesnow usually is packed with snow, when the vehicle is moving.Accordingly, there are instances where when sudden stops are desired,skidding and indeed overturning of the vehicle occur. By incorporatingan ABS system in the present invention snowmobile, the amount of brakepressure that is applied to brake pad 80 is limited and brake slippageis allowed. Thus, the snow that is packed between adjacent ribs of belt30 is thrown off when the rider actuates the brake system. As aconsequence, better traction and thereby better control are obtained bythe ABS system equipped snowmobile of the instant invention.

Insofar as the instant invention is subject to many variations,modification and changes in detail, it is the intention of the inventorsthat all matters described throughout this specification and shown inthe accompanying drawings be interpreted as illustrative only and not ina limiting sense. Accordingly, it is intended that this invention belimited only by the spirit and scope of the hereto appended claims.

What is claimed is:
 1. A vehicle comprising: a body onto which at leastone rider rides; a frame to which slide tracks are mounted; a beltmounted about said slide tracks and driven to provide movement for saidvehicle; a suspension system including at least one fluid actuateddevice operatively connecting said frame to said body, said fluidactuated device adjustable manually by said rider to effect a givenstiffness for his ride or automatically to maintain a preset optimalcushioned ride for said rider irrespective of the type of movement ofsaid vehicle; and a pair of skis movably attached to said vehicle bodyfor providing said rider controlled steered movement of said vehicle, atleast one fluid actuated cylinder connecting each of said skis to saidbody, said at least one fluid actuated device adjustable at any time toeffect a stabilized movement for said one ski independent of the otherof said skis.
 2. A vehicle comprising: a body onto which at least onerider rides; a frame to which slide tracks are mounted; a belt mountedabout said slide tracks and driven to provide movement for said vehicle;a suspension system including at least one fluid actuated deviceoperatively connecting said frame to said body, said fluid actuateddevice adjustable manually by said rider to effect a given stiffness forhis ride or automatically to maintain a preset optimal cushioned ridefor said rider irrespective of the type of movement of said vehicle;wherein said fluid actuated device comprises two fluid driven cylindersworking cooperatively with each other to provide a variable optimaldistance between said body and said slide tracks; and wherein said twofluid actuated cylinders are individually actuated.
 3. A snowmobilecomprising: a body for supporting at least one rider; a frame to whichslide tracks are mounted for supporting said body; a belt mounted aboutsaid slide tracks and driven to provide movement for said snowmobile; atleast one fluid actuated device connecting said body to said frame, saidfluid actuated device adjustable manually by said rider to effect agiven stiffness for his ride or automatically to adjust the relativedistance separating said body and said frame so as to maintain acushioned ride for said rider; and a pair of skis movably attached tosaid body for providing said rider controlled steered movement of saidsnowmobile, at least one fluid actuated cylinder connecting each of saidskis to said body, said at least one fluid actuated device adjustable atany time to effect a stabilized movement for said one ski independent ofthe other of said skis.